Direct current (DC) brushless motors have been used in a variety of electronic and industrial applications such as automotive applications where the motor drives a fan to cool an automobile engine or HVAC applications where the motor drives a fan in a blower unit. Conventional brushless motors typically include a stator comprising a core having windings, a rotor having permanent magnets, and a shaft supporting the motor with respect to the stator. At least two ball bearing assemblies are generally employed to rotatably couple the shaft to either the stator or the rotor. The bearing assemblies are necessary to counteract the radial, axial and moment forces associated with the coupling of the rotor to the stator.
The use of at least two ball bearing assemblies adds to the cost and assembly time associated with conventional brushless motors. Two ball bearing assemblies require two sets of bearing retainers, two pieces of oil felt, additional lubricant, and a number of other components necessary to maintain the rotatable connection within the motor. Therefore, there is a need for a brushless motor which requires only a single bearing assembly to rotationally support the rotor with respect to the stator. Further, there is a need for brushless motor structure which can be easily assembled.
Conventional brushless motors often include electronic circuitry mounted within the motor. The electronic circuitry drives current through the windings of the stator to generate a magnetic field which effects rotation of the rotor. Such electronic circuitry generates heat which must be dissipated from the motor via large, expensive heat sinks. Thus, there is also a need for increased heat dissipation in conventional brushless motors.